The present invention relates to a gas-type power breaker for interrupting a power circuit utilizing sublimation of a gas starting agent for example, and more particularly, to a gas-type power breaker which can easily be assembled and which can forcibly and reliably interrupt a power circuit when abnormal conditions were encountered or a short circuit, collision of vehicle or the like occurred.
Japanese Patent Application Laid-open No. H11-301376 discloses a structure in which in a gas-type power breaker which can forcibly interrupt a power circuit utilizing sublimation of a gas starting agent when abnormal conditions were encountered or a short circuit, collision with a vehicle or the like occurred. However, a structure of the above-described conventional gas-type power breaker has the following problem. That is, since the shaft is held only by contacting load of the terminals, there is an adverse possibility that the shaft may malfunction due to an impact or vibration other than sublimation of the gas-starting agent.
Further, since the gas pressure is not released until the shaft moves to the interruption position, it is necessary to insert the nozzle into the shaft deeply, and there is a problem that it is difficult to assemble this kind of gas-type power breaker.
In view of the above circumstances, it is an object of the present invention to provide a gas-type power breaker which can easily be assembled and which can forcibly and reliably interrupt a power circuit only when abnormal conditions were encountered or a short circuit, collision of vehicle or the like occurred.
To achieve the above object, according to a first aspect of the present invention, there is provided a gas-type power breaker comprising a pair of terminals inserted in a power circuit for connecting a battery of a vehicle and loads provided in various portions of the vehicle, a shaft slidably inserted in a base body holding the terminals and capable of connecting and separating the terminals with and from each other by a sliding movement of the shaft, and circuit interrupting means for sliding the shaft from an initial position where the terminals are connected to each other to an interruption position where the terminals are separated from each other when a circuit interruption signal is input, thereby interrupting the power circuit, wherein a front cover having a resilient locking arm is mounted to one end of the shaft, the base body is formed with an engaging projection, and the resilient locking arm and the engaging projection are engaged with each other at the initial position of the shaft, and mounted in the vehicle.
According to the first aspect, the resilient locking arm of the front cover and the engaging projection of the base body are engaged with each other at the initial position of the shaft inserted in the base body, it is possible to prevent the shaft from sliding by factor such as impact and vibration other than sublimation of the gas-starting agent.
Accordingly, since the generated gas is compressed in the base body, and the shaft is slid and moved by the pressure generated by the compressed gas, it is unnecessary to insert the nozzle into the shaft deeply unlike the conventional technique. Since the ignitor is press-fitted into the rear end of the shaft, a nozzle itself is unnecessary, and it is possible to easily assemble this kind of gas-type power breaker.
According to a second aspect of the present invention, a gas vent hole capable of discharging out gas generated by sublimation of a gas-starting agent is formed on the base body closer to one of the terminals mounted to the front cover.
With the second aspect, when the sliding movement of the shaft is started by the gas generated by the sublimation of the gas-starting agent, the generated gas can be discharged out from the gas vent hole concurrently. Therefore, it is possible to obtain an arc-extinguishing effect for restraining an arc from being generated between the terminals by the gas pressure.
According to a third aspect of the present invention, the front cover is assembled such that it can turn around the shaft, and is capable of selecting a mounting position and a separating position with respect to the shaft by turning operation of the front cover, the front cover can be secured to a reset knob mounted to a tip end of the shaft in the mounting position with respect to the shaft, and the front cover can be pulled out from the reset knob in the separating position.
With the third aspect, the front cover is mounted such that it can rotate around the shaft, and the mounting position and the separating position with respect to the shaft can be selected by turning the front cover. In the mounting position with respect to the shaft, the front cover can be secured to the reset knob of the shaft, and in the separating position, the front cover can be pulled out from the reset knob. Therefore, the power circuit can be opened manually irrespective of movement of the shaft. Further, the power circuit can be closed by returning the reset knob into the base body while pushing the stopper which jumped out from the reset knob into the reset knob.